1. Field of the Invention:
The present invention relates to a rotary drafting apparatus for use in a spinning machine, and more particularly to a tooth structure adapted for control rollers of the drafting apparatus of the above type.
2. Description of the Prior Art:
In order to accomplish combing of silver, it has been put into practice to interpose control rollers between a pair of back or feed rollers and a pair of front or drafting rollers. Each of these control rollers is formed with a number of needles or teeth on its circumference. The control rollers thus formed are grouped into a few of vertical pairs, each of which is composed of top and bottom rollers, and the resultant pairs are arranged in cascade for the desired combing treatment. In the known control rollers, however, the silver is liable to be partially seized and carried back upstream by their needles or teeth, thus making it impossible to expect smooth and efficient combing of the silver. Such seizure of fiber by the teeth will invite unevenness in the thickness of the silver and accordingly substantial reduction in overall efficiency of the drafting apparatus.